JP4036850B2 - Receiver module - Google Patents

Description

  The present invention relates to a light receiving module suitable for an optical remote controller.

In recent years, in many indoor devices such as audio devices and television receivers, infrared light is resistant to noise and can transmit a large amount of information, so an optical remote controller using a light emitting diode and a light receiving element has been used. . A light receiving module used in the optical remote controller is disclosed in Patent Document 1 as shown in FIG. 3, for example. In this figure, a light receiving element 31 and a circuit element 32 are placed on a circuit board 33 and stored in a shield case 34. The light receiving element 31 includes a frame 35, a back electrode 36, a P ⁺ layer 37, a semiconductor substrate 38, an N layer 39, an insulating layer 40, and a surface electrode 41.
JP-A-3-72730

  When the above-described light receiving module 42 is built in, for example, a television receiver, a predetermined input optical signal easily picks up noise (16.6 kHz) of the flyback transformer of the receiver. For this purpose, the shield case 34 is provided with the mesh structure 43 and the filter 44. However, these components attenuate the input optical signal and increase the cost. In order to eliminate this drawback, the present inventor eliminated the mesh structure 43 and the filter 44, provided an electrode 45 (not shown) for wire bonding on the semiconductor substrate 38 apart from the surface electrode 41, and contacted it. A transparent electrode 46 was provided, and a voltage was applied through a fine metal wire (not shown) connected to the electrode 45. However, as a result of experiments, this structure also has the first drawback that it is easy to pick up the noise of the television receiver. Further, since the surface electrode 41 and the electrode 45 are provided, and the transparent electrode 46 is further provided, patterning is required twice, and there is a second defect that is difficult to manufacture.

  Furthermore, since a parallel plate capacitor is formed by the N layer 39, the insulating layer 40, and the transparent electrode 46, a part of the input optical signal flows through the capacitor, so that the output current of the optical signal is reduced. Therefore, there is a third drawback that the reachable distance for receiving light is as small as 5 to 6 m. Accordingly, the present invention provides a light receiving element that is difficult to pick up noise, has a small capacitor capacity, and is easy to manufacture in consideration of such conventional drawbacks.

  The present invention relates to a light receiving module comprising a light receiving element formed of a PIN photodiode and a metal frame on which the light receiving element is mounted. The light receiving element has a first conductivity type on one surface of the semiconductor substrate and the semiconductor substrate. A diffusion layer formed by diffusing impurities; a high-concentration layer including a second conductivity type impurity formed on one surface of the semiconductor substrate so as to be positioned around the diffusion layer; and one of the semiconductor substrates An insulating layer formed on the surface, and first and second layers provided in contact with the diffusion layer and the high-concentration layer through the first and second through holes of the insulating layer and spaced apart from each other on the insulating layer. The first electrode is provided in a substantially frame shape on the insulating layer except above the diffusion layer, and the first electrode is electrically connected to the metal frame by connection means. It is characterized by.

  The second electrode is provided on the insulating layer in a range excluding the upper side of the diffusion layer.

  Electromagnetic shielding can be provided by a protective surface having the same potential. Also, the structure is simple and easy to manufacture. Desirably, by providing the second electrode on the insulating layer excluding the upper side of the diffusion layer, the capacitance of the capacitor constituted by the diffusion layer, the insulating layer, and the second electrode is reduced. As a result, the amount of the input optical signal that passes through the capacitor is reduced, so that the output current of the optical signal is increased, and the light receiving distance is increased to 8 to 9 m when incorporated in a light receiving module or the like.

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view of a light-receiving module using the light-receiving element according to this embodiment, and FIG. 2 is a cross-sectional view taken along AA in FIG. In these figures, the light receiving element is made up of, for example, a PIN photodiode, and a diffusion layer 3 is provided inside the substantially central surface of the semiconductor substrate 2 made of silicon containing P-type impurities having an impurity concentration of 4 × 10 ¹² cm ⁻³ or less. It has been. The diffusion layer 3 is diffused so that the concentration of the first conductivity type impurity such as boron is about 1 × 10 ²⁰ cm ⁻³ , the depth is 1 to 2 μm, and the sheet resistance is 10 to 50Ω / □. About 20Ω / □ is desirable.

The high concentration layer 4 is located in the periphery of the diffusion layer 3 and is provided inside the surface of the semiconductor substrate 2 and contains a second conductivity type impurity. The high concentration layer 4 is made of, for example, phosphorus having an impurity concentration of about 1 × 10 ²⁰ cm ⁻³ and a depth of 1 to 2 μm.

The blocking layer 5 is located in the periphery of the high concentration layer 4 and is provided inside the surface of the semiconductor substrate 2. For example, the first conductivity type impurity such as boron is deep so that the impurity concentration is about 1 × 10 ²⁰ cm ^−3. It is added to 2 to 4 μm. In this way, when viewed from the plane, the diffusion layer 3 is formed in, for example, a substantially rectangular shape having a width of 2000 μm and a length of 1000 μm. For example, the high concentration layer having a width of about 20 μm and the blocking layer 5 are formed in a substantially frame shape.

  The first electrode 6 is made of aluminum, for example, and is formed so as to be in contact with the diffusion layer 3. The second electrode 7 is made of, for example, aluminum, and is formed at a position in contact with the high concentration layer 4 and excluding the upper side of the diffusion layer 3.

  The insulating layer 8 is formed on the surface of the semiconductor substrate 2 excluding the first electrode 6 and the second electrode 7, and is made of, for example, silicon dioxide. This insulating layer 8 protects the surface of the semiconductor substrate 2 and serves to prevent reflection. In this way, the first and second electrodes 6 and 7 are in contact with the diffusion layer 3 and the high concentration layer 4 through the first and second through holes 6a and 7a of the insulating layer 8, respectively. Are provided apart from each other.

  The leakage current flowing through the boundary between the diffusion layer 3 and the insulating layer 8 is blocked by the blocking layer 5 formed around the high concentration layer 4.

  The first electrode 6 is substantially entirely formed on the insulating layer 8 in a substantially frame shape with one part missing in a range excluding the upper side of the diffusion layer 3 when viewed from the plane. Thus, since the incident light does not hit the blocking layer 5 due to the blocking of the first electrode 6 positioned on the blocking layer 5, no current is generated around the blocking layer 5. Therefore, predetermined diode characteristics (output current with respect to the applied bias voltage) can be obtained.

The second electrode 7 is formed in a substantially rectangular shape on the insulating layer 8 apart from the first electrode 6 when viewed from the plane. The light receiving element 1 is constituted by these members. In addition, a capacitor is constituted by the high concentration layer 4, the insulating layer 8, and the first electrode 6, but the capacity is extremely small as compared with the conventional one. This is because if the plane area of the high concentration layer 4 is S1 and the plane area of the diffusion layer 3 is S2, S1 = 20 × (2000 + 2000 + 1000 + 1000) = 120,000 μm, S2 = 2000 × 1000 = 2,000,000 μm ² It becomes. Therefore, S1 / S2 = 6%, the plate area to be a capacitor is 6% of the conventional one, and the capacitor capacity is also 6% of the conventional one.

  The first frame 9 is made of a metal plate, and the light receiving element 1 is placed via the conductive adhesive 10. The connecting means 11 is made of a fine metal wire such as gold, and is wired between the first electrode 6 and the first frame 9. That is, the first electrode 6 and the semiconductor substrate 2 are electrically connected by the connecting means 11.

  The circuit element 12 is placed on the first frame 9 via a conductive adhesive 13. The circuit element 12 includes a back electrode 14, a P-type semiconductor substrate 15, a composite layer 16, and surface electrodes 17, 18, 19, and 20.

  The fine metal wire 21 is wired between the surface electrode 17 of the circuit element 12 and the second electrode 7 of the light receiving element 1. Both the second frame 22 and the third frame 23 are made of metal plates and are connected to the surface electrodes 18 and 19, respectively.

  The resin 24 is made of epoxy resin or the like and is provided so as to cover the periphery of the light receiving element 1, the circuit element 12, and the first, second, and third frames 9, 22, and 23. The resin 24 is mixed with a filter dye that transmits infrared light but attenuates visible light in accordance with the sensitivity characteristics of the light receiving element 1. Desirably, the upper surface of the resin 24 is formed in a convex lens shape so that a larger amount of light is collected in the diffusion layer 3. The light receiving module 25 is configured by these members.

  Next, the operation of the light receiving module 25 will be described. An input optical signal 26 sent from a light emitting module (not shown) of the optical remote controller, modulated with an electrical signal and superimposed on infrared light, enters the diffusion layer 3 of the light receiving element 1 through the resin 24. At this time, a constant reverse bias voltage is applied to the light receiving element 1 by an ABLC (auto bias logic level controller) in the circuit element 12. An optical signal output according to the intensity of the input optical signal 26 enters the circuit element 12 through the thin metal wire 21. The optical signal output is output from the second frame 22 as an electric signal detected by an amplifier, a detection circuit, a waveform shaping circuit, and the like in the circuit element 12.

  In the above description, a PIN photodiode is taken as an example. However, the present invention is not limited to this, and can be applied to a general photodiode (light receiving element), and also applied to a light receiving element having a polarity opposite to that of the present embodiment. it can.

  As described above, a PIN photodiode is formed by the first conductive type diffusion layer provided in the approximate center of the semiconductor substrate, the semiconductor substrate, and the second conductive type high concentration layer provided in the periphery of the diffusion layer. . By covering the substantially entire surface of the light receiving element with the first electrode and electrically connecting the semiconductor substrate serving as the back surface of the light receiving element and the first electrode, the entire surface of the light receiving element has the same potential. Therefore, the light receiving element placed in the electromagnetic field by the flyback transformer or the like of the television receiver is electromagnetically shielded by the protective surface having the same potential. Further, since only the first and second electrodes are provided on the insulating layer, only one patterning is required, and no conventional back electrode is provided, so that the structure is simple and the manufacturing is easy.

  Desirably, by providing the second electrode on the insulating layer excluding the upper side of the diffusion layer, the capacitance of the capacitor constituted by the diffusion layer, the insulating layer, and the second electrode is reduced. As a result, the amount of the input optical signal that passes through the capacitor is reduced, so that the output current of the optical signal is increased, and the light receiving distance is increased to 8 to 9 when incorporated in a light receiving module or the like.

  It can be used as a light receiving module suitable for an optical remote controller.

It is sectional drawing of the light reception module using the light receiving element which concerns on the Example of this invention. It is AA sectional drawing of FIG. It is sectional drawing of the conventional light reception module.

Explanation of symbols

2 Semiconductor substrate 3 Diffusion layer 4 High concentration layer 6 First electrode 7 Second electrode 8 Insulating layer

Claims (2)

  In a light receiving module comprising a light receiving element composed of a PIN photodiode and a metal frame on which the light receiving element is mounted, the light receiving element has a semiconductor substrate and a first conductivity type impurity diffused on one surface of the semiconductor substrate. A diffusion layer formed on one surface of the semiconductor substrate, a high-concentration layer containing a second conductivity type impurity formed so as to be positioned around the diffusion layer, and a semiconductor substrate. And a first electrode and a second electrode provided in contact with the diffusion layer and the high-concentration layer through the first and second through holes of the insulating layer and spaced apart from each other on the insulating layer. The first electrode is provided in a substantially frame shape on the insulating layer except for the upper side of the diffusion layer, and the first electrode is electrically connected to the metal frame by connection means. Receiver module   The light receiving module according to claim 1, wherein the second electrode is provided on the insulating layer in a range excluding the upper side of the diffusion layer.

Images